Technology

Babbling with your baby just got scientific

If you've ever caught yourself using baby talk with a young infant, you're not alone. New research is looking into this so-called "motherese." That's the high-pitched, sing-songy chatter that many parents, not just moms, use when they speak to their babies.

What was the main finding of this new research from Princeton University?

The research looked into understanding that higher pitched kind of baby talk that almost mimicks a child's voice. This has been studied in a lot of ways in terms of rhythm and pitch. It has been shown that baby talk helps babies break up the sounds of a language into unique words. It helps them learn distinct words, semantics, rhyming and sounds.

What hadn't really been looked at was the timbre of the mother's voice.That's why the lead author on this new study Elise Piazza got involved.

"Mothers shift their timbre which is the unique sort of fingerprint of a human voice when speaking to their infants compared to when they're speaking to other adults," said Piazza. "And what was most interesting to us, was that this timbre shift was highly similar across mothers who spoke ten diverse languages from all around the world."

The researchers studied subjects who used a variety of languages including Mandarin, Polish, Spanish and English. The moms they studied were living in the New Jersey area around Princeton University, but each used their native tongues for their primary communication with their babies. And no matter what, a change in timbre was measured.

What exactly is timbre?

Piazza is uniquely qualified to explain timbre given she's both a neuroscientist and a clarinet player. "I'm a musician and whenever I think about the nice sort of warm reediness of the clarinet that I play versus the sort of bright sharper sounds of a cymbal, or kind of a buzzy brass sound. These are all really important features for understanding musical emotion and for describing different voices, and they all have to do with timbre."

It's timbre that allows you to recognize your friends voice over a stranger's. It's what makes two artists, singing the exact same note, sound different to us. And, t turns out, the mothers in the study all adjusted their timbre when they talked to their babies.

How did the researchers measure the changes in timbre?

This was where things got really scientific. The researchers would take recordings of each individual speaking in their normal adult talking voice, and then another recording when they engaged in "motherese." Then the scientists let a computer do the rest of the work.

Piazza explains: "We take these natural clips of speech, and then we use a computer algorithm to basically pull out a signature of timbre from each of those clips for each mother across the different languages. And once we have this sort of statistical representation of the timbre fingerprint, we use a machine-learning algorithm … basically told us that we had a statistical difference between the timbre fingerprints of motherese and adult-directed speech. and that same sort of statistical pattern was consistent across the languages."

No matter what language you speak, you probably do this with your baby.

Why do moms do that?

That's not entirely clear yet. We know that rhythm and pitch change when we talk to a baby, We use this high pitch and sing-songy voice when we say, 'Hello boo boo, how was your day?' That helps babies identify the words. The reason for the timbre changes aren't so clear.

One hypothesis is that it simply allows recognition of the mother's voice. It may be that there's a specific timbre fingerprint in the womb and it allows babies to hear their mothers voice as distinct, but no one has demonstrated that yet.

What about dads?

Likely the same thing goes for dads but a mother and her milk is much more essential to early survival for a baby than his or her dad, at least evolutionarily speaking. So it may turn out to be more of a mother-specific phenomenon. But moms and dads alike are known to get into baby talk mode.

What's next to understand so-called 'motherese?'

The next big thing to study is how babies interpret these timbre changes and see how they affect language learning and potentially bonding. That's easier said than done.

Most of the studies in infant language learning use 7- to -12-month-old subjects who can't exactly tell you what they're learning. But there are new ways to look at activity in babies' brain regions as well as eye tracking to can help us figure out if that crazy baby talk is really helping our little ones or just making us look silly.